The present invention relates to a system for managing diabetes. More particularly, the present invention relates to an automated system for determining the timing and amount of insulin administration to a subject in the treatment of diabetes.
Typically, insulin therapy is based upon a set of rules that employ periodic glucose measurements to make insulin recommendations to manage glucose levels. The rules are based on estimates of an individual subject""s response to carbohydrates, insulin and exercise. In practice, these rules are used to present an initial therapy. The subject then individualizes this therapy with the help of a health-care provider by analyzing the glycemic results achieved to date. This data is in the form of a written or electronic logbook that the subject maintains regarding exercise, food consumption, insulin doses and glucose measurements. The rules are applied for administering insulin and/or carbohydrates based on experience and abnormal glucose values. Rules are generally updated when the therapy results in degraded blood glucose control.
Electronic diabetes management systems have been developed to assist subjects in the implementation of insulin administration regimens. See, for example U.S. Pat. Nos. 5,019,974; 4,731,726; 5,822,715; 5,840,020. See also, EP 1 102 194 A2, the disclosure of which is incorporated herein by reference.
According to the present invention, a system for providing glycemic control to a subject is provided. The system comprises an insulin delivery unit, a glucose sensor, and a control unit. The control unit includes a processor unit that receives glucose value readings from the glucose sensor, executes an algorithm that predicts a glucose value at a pre-determined time in the future, compares that predicted glucose value to a pre-determined glucose value range, and determines a corrective amount of insulin to be administered when the predictive glucose value lies outside of the pre- determined glucose value range. The control unit also includes a communication unit that transmits the corrective amount to the delivery unit. In at least one embodiment, a predictive model is provided that is based on the following equation: xcex94G=xe2x80x94(TotallnsuRemainxe2x80x94BasalReq) * Sensitivity, wherein xcex94G=future change in glucose level at a pre-determined time, TotalInsuRemain=amount of insulin remaining in the subject""s system at the current time, BasalReq=how much insulin the subject is estimated to need at the pre-determined time, and Sensitivity=Insulin sensitivity.
In addition, a system for providing glycemic control to a subject is provided in accordance with the present invention. The system comprises a sensor formed to conduct a glucose measurement of a subject, a control unit that includes a processor unit that is formed to accept data from the subject on insulin sensitivity and basal rate, to execute an algorithm that generates a predictive value of the subject""s glucose level at a predetermined time in the future based upon the glucose measurement from the sensor and the data, and to compute a corrective action when the predictive value lies outside of a predetermined target range. The system also includes an insulin delivery unit in communication with the control unit. The delivery unit is formed to administer automatically a dosage of insulin to the subject based upon the computed corrective action of the control unit.
Still further in accordance with the present invention a method for providing glycemic control to a subject is provided. The method comprises the steps of determining the glucose value of a subject and inputting the glucose value into at least one processor. The at least one processor is formed to execute at least one algorithm that anticipates the future effects of insulin that has been previously delivered to the subject, to incorporate constraints on insulin delivery and glucose deviations, and to determine a corrective amount of insulin to be administered when the predictive glucose value lies outside of the pre-determined glucose value range. Next, the desired insulin dosage is delivered automatically to the subject and both the determining and inputting steps are repeated.
In addition, a system for providing glycemic control to a subject is provided. The system comprises means for delivering insulin to a subject, means for determining a glucose value from the subject, and a control unit including a processor unit that is formed to compare the glucose value to a predetermined glucose value range. The processor unit is also formed to determine a corrective amount of insulin to be administered when the predictive glucose value lies outside of the pre- determined glucose value range and to transmit the corrective amount to the delivering means.
According to another embodiment of the present invention a system for predicting a future glucose value of a subject at a predetermined time is provided. The system comprises a control unit that includes a processor unit formed to predict the future glucose value with an algorithm xcex94G=xe2x80x94(TotallnsuRemainxe2x80x94BasalReq) * Sensitivity, wherein xcex94G=future change in glucose levels at a pre-determined time, TotalInsuRemain=amount of insulin remaining in the subject""s system at a current time, and BasaiReq=how much insulin the subject is estimated to need to maintain the current glucose level, and Sensitivity=Insulin sensitivity.
According to still another embodiment of the present invention a system for recommending an insulin dose that compensates for meals for a subject is provided. The system comprises a control unit that includes a processor unit formed to compensate for meals with a feedforward algorithm Dose=carbohydrates * insulin-to-carb-ratio * xcex1meal typexe2x80x94intercept, wherein Dose=Insulin dose, carbohydrates=grams of carbohydrates, insulin-to-carb-ratio=Insulin to Carbohydrate Ratio, xcex1meal type=meal dependent scaling factor, and intercept=intercept to allow a linear fit for sizes of the meals.
Additional features of the invention will become apparent to those skilled in the art upon consideration of the following detailed description of the preferred embodiment exemplifying the best mode of carrying out the invention